Liquid crystal display device

ABSTRACT

A liquid crystal display device comprising a pair of substrates with liquid crystal layer therebetween, a plurality of gate signal lines and a plurality of drain signal lines formed on one of the pair of substrates, at least a pixel electrode and a plurality of counter electrodes formed on the one of the pair of substrates in each pixels, at least one of the plurality of counter electrodes extend along a drain signal line overlapping to the drain signal lines with at least one of an insulation film therebetween, and the drain signal line has two or more regions which differ in distance between a surface of the drain signal line and the counter electrode.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a liquid crystal display device,and more particularly to a so-called in-plane type liquid crystaldisplay device.

[0003] 2. Description of the Related Art

[0004] In a so-called in-plane type liquid crystal display device, apair of substrates are arranged to face each other while sandwichingliquid crystal therebetween, a pixel electrode and a counter electrodewhich are disposed close to each other are formed on each pixel regionprovided to a liquid-crystal-side surface of one substrate out of thepair of substrates, and the behavior of the liquid crystal is controlledin response to parallel components of an electric field to the substratewhich is generated between these electrodes.

[0005] As such a liquid crystal display device adopting an active matrixtype, there has been known a liquid crystal display device in which, onthe liquid-crystal side of one substrate, each pixel region is definedby a region which is surrounded by a plurality of gate signal lineswhich are arranged in parallel and a plurality of drain signal lineswhich cross the gate signal lines and are arranged in parallel. Further,in each pixel region, a thin film transistor which is operated inresponse to a scanning signal from the gate signal line, a pixelelectrode to which a video signal is supplied from the drain signal linethrough the thin film transistor, and a counter electrode to which avoltage signal constituting reference with respect to the video signalis supplied are formed.

[0006] Then, the pixel electrode and the counter electrode arerespectively formed in a strip shape extending in one direction and theyare formed of a group consisting of a plurality of electrodes in whichthe pixel electrode and the counter electrode are arranged alternately.

[0007] Further, in such a constitution, there has been known the counterelectrodes which are formed such that the counter electrodes areoverlapped to the drain signal lines in the running direction of thedrain signal lines by way of an insulation film.

[0008] A line of electric force of the electric field from the drainsignal line is configured to be terminated to the counter electrodewhich is formed to be overlapped to the drain signal line, while theline of electric force of the electric field is configured to be notterminated to the pixel electrode which is arranged close to the counterelectrode. This is because that when the line of electric force of theelectric field is terminated to pixel electrode, this generates noises.

SUMMARY OF INVENTION

[0009] However, with respect to the liquid crystal display device havingsuch a constitution, to make the counter electrode have theabove-mentioned function, it is necessary to form the counter electrodesuch that a width thereof is larger than a width of the drain signalline.

[0010] Accordingly, capacitance of the drain signal line with respect tothe counter electrode (parasitic capacitance) is increased and hence, ithas been pointed out that the delay of waveform is generated withrespect to the video signal supplied to the drain signal line.

[0011] In this case, the delay of waveform of the drain signal line isproportional to a product of resistance R of the drain signal line andthe parasitic capacitance C. Then, to improve the delay, it is effectivethat making at least one of the resistance R and the parasiticcapacitance C to be small.

[0012] However, in case that the counter electrode is present above thedrain signal line, even when the width of the drain signal line isincreased so as to reduce the resistance R of the drain signal line, theparasitic capacitance C thereof with the counter electrode is increasedcorresponding to the reduction of the resistance R and, as a result,there arises a situation that the delay of waveform cannot be reduced.In other words, there are trade-off relation.

[0013] The present invention has been made in view of such circumstancesand one advantage of the present invention lies in the reduction of acapacitance of a drain signal line with respect to a counter electrode.

[0014] To briefly explain the summary of typical inventions among theinventions disclosed in the present application, they are as follows.

[0015] (1)

[0016] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0017] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality of drainsignal lines which cross the gate signal lines and are arranged inparallel are formed;

[0018] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0019] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that the drain signal line hasregions which differ in at least two or more stages with respect to adistance between a surface of the drain signal line which faces thecounter electrode and the counter electrode.

[0020] (2)

[0021] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0022] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality of drainsignal lines which cross the gate signal lines and are arranged inparallel are formed;

[0023] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0024] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that a taper which is flaredtoward a ground layer side of the drain signal line is formed on atleast a side wall face of one of respective sides in the runningdirection of each drain signal line.

[0025] (3)

[0026] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0027] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality oftwo-layered conductive drain signal lines which cross the gate signallines and are arranged in parallel are formed;

[0028] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0029] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that a taper which is flaredtoward a ground layer side of the drain signal line is formed on atleast a side wall face of one of respective sides in the runningdirection of a conductive layer which constitutes a lower layer side ofthe drain signal line.

[0030] (4)

[0031] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0032] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality of drainsignal lines which cross the gate signal lines and are arranged inparallel are formed;

[0033] the drain signal line has a two-layered structure including aconductive layer which constitutes a lower layer made of Al or an alloythereof;

[0034] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0035] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that a taper which is flaredtoward a ground layer side of the drain signal line is formed on atleast a side wall face of one of respective sides in the runningdirection of the conductive layer which constitutes the lower layer ofthe drain signal line.

[0036] (5)

[0037] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0038] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality oftwo-layered conductive drain signal lines which cross the gate signallines and are arranged in parallel are formed;

[0039] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0040] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that by etching a conductivelayer which constitutes a lower layer of the drain signal line using aconductive film which constitutes an upper layer as a mask, tapers whichare flared toward a ground layer side of the drain signal line areformed on side wall faces of the conductive film which constitutes thelower layer of the drain signal line.

[0041] (6)

[0042] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0043] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality of drainsignal lines which cross the respective gate signal lines and arearranged in parallel are formed;

[0044] the drain signal line has a three-layered structure in which anintermediate layer is formed of a conductive layer made of Al or analloy thereof and an uppermost layer and a lowermost layer are formed ofconductive layers made of material other than Al or an alloy thereof,

[0045] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0046] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that a width of the conductivelayer which constitutes the lowermost layer is wider than a width of theconductive layer which constitutes the uppermost layer, and a width ofthe conductive layer which constitutes the intermediate layer is changedfrom the width of the conductive layer which constitutes the lowermostlayer to the width of the conductive layer which constitutes theuppermost layer.

[0047] (7)

[0048] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0049] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality of drainsignal lines which cross the gate signal lines and are arranged inparallel are formed;

[0050] the drain signal line has a three-layered structure in which anintermediate layer is formed of a conductive layer made of Al or analloy thereof and an uppermost layer and a lowermost layer are formed ofconductive layers made of material other than Al or an alloy thereof,

[0051] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes whichgenerate electric fields between the pixel electrodes and the counterelectrodes are formed on the pixel region; and

[0052] the counter electrodes include the counter electrodes whichextend in the running direction of the drain signal lines by way of aninsulation film and are overlapped to the drain signal lines, and thedrain signal lines are constituted such that a width of the conductivelayer which constitutes the lowermost layer is wider than a width of theconductive layer which constitutes the uppermost layer, and a widthbetween side wall surfaces of the conductive layer which constitutes theintermediate layer is changed from the width of the conductive layerwhich constitutes the lowermost layer to the width of the conductivelayer which constitutes the uppermost layer, and oxide films are formedon the side wall surfaces.

[0053] (8)

[0054] A liquid crystal display device according to the presentinvention is, for example, characterized in that:

[0055] on a liquid-crystal-side surface of one substrate of respectivesubstrates which are arranged to face each other in an opposed mannerwhile sandwiching liquid crystal therebetween, a plurality of gatesignal lines which are arranged in parallel and a plurality of drainsignal lines which cross the gate signal lines and are arranged inparallel are formed;

[0056] regions which are surrounded by the respective signal linesconstitute pixel regions, and a thin film transistor which is operatedin response to scanning signals from the gate signal lines, pixelelectrodes to which video signals are supplied from the drain signallines through the thin film transistor, and counter electrodes to whichsignals which constitute a reference with respect to the video signalsare supplied through counter voltage signal lines are formed on eachpixel region; and

[0057] the counter voltage signal lines include the counter voltagesignal lines which extend in the running direction of the gate signallines by way of an insulation film and are overlapped to the gate signallines, and the gate signal lines are constituted such that a taper whichis flared toward a ground layer side of the gate signal line is formedon at least a side wall face of one of respective sides in the runningdirection of each gate signal line.

[0058] (9)

[0059] A liquid crystal display with a pair of substrates with liquidcrystal layer therebetween, a plurality of gate signal lines and aplurality of drain signal lines formed on one of the pair of substrates;at least a pixel electrode and a plurality of counter electrodes formedon the one of the pair of substrates in each pixels, wherein at leastone of the plurality of counter electrodes extend along a drain signalline overlapping to the drain signal lines with at least one of aninsulation film therebetween, and the drain signal line has two or moreregions which differ in distance between a surface of the drain signalline and the counter electrode.

[0060] (10)

[0061] A liquid crystal display device with a pair of substrates withliquid crystal layer therebetween, a plurality of gate signal lines anda plurality of drain signal lines formed on one of the pair ofsubstrates, at least a pixel electrode and a plurality of counterelectrodes formed on the one of the pair of substrates in each pixels,wherein at least one of the plurality of counter electrodes extend alonga drain signal line overlapping to the drain signal lines with at leastone of an insulation film therebetween, the drain signal line has atleast a taper portion in a cross-section view at width direction of thedrain signal line.

[0062] (11)

[0063] A liquid crystal display device according to (10), a width of thedrain signal line is wider at a substrate side of the drain signal lineformed thereon than a liquid crystal layer side.

[0064] (12)

[0065] A liquid crystal display device according to (10), the drainsignal line have a multiplayer structure of a lower layer faced to thesubstrate and an upper layer, and the width of the lower layer is widerthan a width of the upper layer.

[0066] (13)

[0067] A liquid crystal display device with a pair of substrates withliquid crystal layer therebetween, a plurality of gate signal lines anda plurality of drain signal lines formed on one of the pair ofsubstrates, at least a pixel electrode and a plurality of counterelectrodes formed on the one of the pair of substrates in each pixels,wherein the drain signal line has a three-layered structure in which anintermediate layer is formed of a conductive layer made of Al or analloy thereof and an uppermost layer and a lowermost layer are formed ofconductive layers made of material other, than Al or an alloy thereof,at least one of the plurality of counter electrodes extend along a drainsignal line overlapping to the drain signal lines with at least one ofan insulation film therebetween, and width of the lowermost layer iswider than a width of the uppermost layer, and a width of theintermediate layer gradually change its from the width of the lowermostlayer to the width of the uppermost layer.

[0068] (14)

[0069] A liquid crystal display device according to (13), oxide filmsformed on the side wall of the surface of the intermediate layer.

[0070] (15)

[0071] A liquid crystal display device with a pair of substrates withliquid crystal layer therebetween, a plurality of gate signal lines anda plurality of drain signal lines formed on one of the pair ofsubstrates, at least a pixel electrode and a plurality of counterelectrodes formed on the one of the pair of substrates in each pixels,at least one of the plurality of counter electrodes extend along a gatesignal line overlapping to the gate signal lines with at least one of aninsulation film therebetween, the gate signal line has at least a taperportion in a cross section view at width direction of the gate signalline.

[0072] (16)

[0073] A liquid crystal display device according to (15), a width of thegate signal line is wider at a substrate side of the gate signal lineformed thereon than a liquid crystal layer side.

[0074] (17)

[0075] A liquid crystal display device according to (15), the gatesignal line have a multiplayer structure of a lower layer faced to thesubstrate and an upper layer, and the width of the lower layer is widerthan a width of the upper layer. (18)

[0076] A liquid crystal display device with a pair of substrates withliquid crystal layer therebetween, a plurality of gate signal lines anda plurality of drain signal lines formed on one of the pair ofsubstrates, at least a pixel electrode and a plurality of counterelectrodes formed on the one of the pair of substrates in each pixels,the gate signal line has a three-layered structure in which anintermediate layer is formed of a conductive layer made of Al or analloy thereof and an uppermost layer and a lowermost layer are formed ofconductive layers made of material other than Al or an alloy thereof, atleast one of the plurality of counter electrodes extend along a gatesignal line overlapping to the gate signal lines with at least one of aninsulation film therebetween, and width of the lowermost layer is widerthan a width of the uppermost layer, and a width of the intermediatelayer gradually change its from the width of the lowermost layer to thewidth of the uppermost layer.

[0077] (19)

[0078] A liquid crystal display device according to (18), oxide filmsformed on the side wall of the surface of the intermediate layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0079]FIG. 1 is a cross-sectional view showing one embodiment of a pixelof a liquid crystal display device according to the present invention.

[0080]FIG. 2 is an equivalent circuit diagram showing one embodiment ofthe liquid crystal display device according to the present invention.

[0081]FIG. 3 is a plan view showing one embodiment of a pixel of aliquid crystal display device according to the present invention.

[0082]FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG.3.

[0083]FIG. 5 is a cross-sectional view showing one embodiment of anessential part of a pixel of the liquid crystal display device accordingto the present invention.

[0084]FIG. 6 is a cross-sectional view showing another embodiment of adrain signal line of the liquid crystal display device according to thepresent invention.

[0085]FIG. 7 is a cross-sectional view showing one embodiment of anessential part of a pixel of the liquid crystal display device accordingto the present invention.

[0086]FIG. 8 is a flowchart showing one embodiment of a manufacturingmethod of a liquid crystal display device according to the presentinvention.

[0087]FIG. 9 is a cross-sectional view showing one embodiment of anessential part of a pixel of the liquid crystal display device accordingto the present invention.

[0088]FIG. 10 is a cross-sectional view showing another embodiment ofthe pixel of the liquid crystal display device according to the presentinvention.

[0089]FIG. 11 is a cross-sectional view showing another embodiment ofthe drain signal line of the liquid crystal display device according tothe present invention.

[0090]FIG. 12 is a cross-sectional view showing another embodiment ofthe pixel of the liquid crystal display device according to the presentinvention.

[0091]FIG. 13 is a cross-sectional view showing another embodiment ofthe pixel of the liquid crystal display device according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0092] Preferred embodiments of a liquid crystal display deviceaccording to the present invention is explained hereinafter inconjunction with drawings.

[0093] Embodiment 1

[0094] <<Equivalent Circuit>>

[0095]FIG. 2 is an equivalent circuit diagram showing one embodiment ofa liquid crystal display device according to the present invention.Although FIG. 2 is the circuit diagram, the drawing is depicted inaccordance with an actual geometric arrangement.

[0096] In the drawing, a pair of transparent substrates SUB1, SUB2 whichare arranged to face each other in an opposed manner while sandwichingliquid crystal therebetween are provided, wherein the liquid crystal issealed by a sealing material SL which also has a function of fixing theother transparent substrate SUB2 to one transparent substrate SUB1.

[0097] On a liquid-crystal-side surface of one transparent substrateSUB1 which is surrounded by the sealing material SL, gate signal linesGL which extend in the x direction and are arranged in parallel in the ydirection and drain signal lines DL which extend in the y direction andare arranged in parallel in the x direction are formed.

[0098] A region which is surrounded by respective gate signal lines GLand respective drain signal lines DL constitutes a pixel region and amass of these pixel regions in a matrix array constitute a liquidcrystal display part AR.

[0099] Further, common counter voltage signal lines CL which run inrespective pixel regions are formed in respective pixel regions whichare arranged in parallel in the x direction. These counter voltagesignal lines CL constitute signal lines which supply a voltage which isused as reference with respect to a video signal to counter electrodesCT in respective pixel regions which will be explained later.

[0100] On each pixel region, a thin film transistor TFT which isoperated in response to a scanning signal from the one-side gate signalline GL and a pixel electrode PX to which a video signal is suppliedfrom the one-side drain signal line DL through the thin film transistorTFT are formed.

[0101] The pixel electrode PX generates an electric field between thepixel electrode PX and the counter electrode CT which is connected tothe counter voltage signal line CL and the optical transmissivity of theliquid crystal is controlled in response to this electric field.

[0102] Respective one ends of the gate signal lines GL extend over thesealing material SL and the extending ends constitute terminals to whichoutput terminals of a vertical scanning driving circuit V are connected.Further, to input terminals of the vertical scanning driving circuit V,signals from a printed circuit board which is arranged outside theliquid crystal display panel are inputted.

[0103] The vertical scanning driving circuit V is constituted of aplurality of semiconductor devices. A plurality of gate signal lines GLwhich are arranged close to each other are formed into a group. Onesemiconductor device is allocated to each group.

[0104] In the same manner, respective one ends of the drain signal linesDL extend over the sealing material SL and the extending ends constituteterminals to which output terminals of the video signal driving circuitHe are connected. Further, input terminals of the video signal drivingcircuit He are configured to receive inputting of signals from a printedcircuit board which is arranged outside the liquid crystal displaypanel.

[0105] This video signal driving circuit He is also constituted of aplurality of semiconductor devices. A plurality of drain signal lines DLwhich are arranged close to each other are formed into a group. Onesemiconductor device is allocated to each group.

[0106] Further, the counter voltage signal lines CL are connected incommon at aright-side end portion in the drawing, for example. Aconnection line extends over the sealing material SL and the extendingend constitutes a terminal CLT. A voltage which constitutes thereference with respect to video signals is supplied from the terminalCLT.

[0107] The respective gate signal lines GL are sequentially selected oneby one in response to the scanning signals from the vertical scanningcircuit V.

[0108] Further, to respective drain signal lines DL, the video signalare supplied at the timing of selection of the gate signal lines GL fromthe video signal driving circuit He.

[0109] In the above-mentioned embodiment, the vertical scanning drivingcircuit V and the video signal driving circuit He are constituted of thesemiconductor devices which are mounted on the transparent substrateSUB1. However, these driving circuits V and He may be constituted ofso-called tape carrier type semiconductor devices which are connectedastride between the transparent substrate SUB1 and the printed circuitboard, for example. Further, when a semiconductor layer of the thin filmtransistor TFT is constituted of poly-crystalline silicon p-Si,semiconductor divices made of the poly-crystalline silicon may be formedon the transparent substrate SUB1 surface together with wiring layers.

[0110] <<Constitution of Pixel>>

[0111]FIG. 3 is a plan view showing one embodiment of the constitutionof the pixel region. Further, FIG. 1 is a cross-sectional view takenalong a line I-I in FIG. 3 and FIG. 4 is a cross-sectional view takenalong a line IV-IV in FIG. 3.

[0112] In respective drawings, on a liquid-crystal-side surface of thetransparent substrate SUB1, first of all, a pair of gate signal lines GLwhich extend in the x direction and are arranged in the y direction inparallel are formed.

[0113] These gate signal lines GL surround a rectangular region togetherwith a pair of drain signal lines DL which are explained later and thisregion constitutes the pixel region.

[0114] Further, simultaneously with the formation of the gate signallines GL, the counter voltage signal line CL which runs parallel to thegate signal lines GL at the center of each pixel region, for example, isformed.

[0115] On the surface of the transparent substrate SUB1 on which thegate signal lines GL and the counter voltage signal lines CL are formedin this manner, an insulation film GI made of SiN, for example, (seeFIG. 1, FIG. 4) is formed such that the insulation film GI also coversthe gate signal lines GL and the counter voltage signal lines CL.

[0116] The insulation film GI has a function of an interlayer insulationfilm for the gate signal lines GL in the regions where the drain signallines DL which are explained later are formed, has a function of a gateinsulation film in the regions where the thin film transistors TFT whichwill be explained later are formed, and has a function of one ofdielectric films in regions where capacitive elements Cstg which will beexplained later are formed.

[0117] Further, on a surface of the insulation film GI, semiconductorlayers AS which are made of amorphous Si, for example, are formed suchthat the semiconductor layers AS are overlapped to portions of the gatesignal lines GL.

[0118] Each semiconductor layer AS constitutes a semiconductor layer ofthe thin film transistor TFT. By forming a drain electrode SD1 and asource electrode SD2 on an upper surface of the semiconductor layer AS,it is possible to constitute a MIS type transistor having an inversestagger structure which uses a portion of the gate signal line as a gateelectrode.

[0119] Here, the drain electrode SD1 and the source electrode SD2 areformed simultaneously with the formation of the drain signal line DL.

[0120] That is, the drain signal lines DL which extend in the ydirection and are arranged in parallel in the x direction are formed,then, portions of the drain signal lines DL are extended over the uppersurfaces of the semiconductor layers AS so as to form the drainelectrodes SD1, and the source electrodes SD2 are formed spaced apartfrom the drain electrodes SD1 by a length of a channel of the thin filmtransistor TFT.

[0121] Here, with respect to the drain signal line DL, tapers which aregradually widened toward the insulation film GI side of the drain signalline DL are formed on side wall faces of respective sides of the drainsignal line DL in the running direction. The reason that such aconstitution is adopted is explained later.

[0122] Further, the source electrode SD2 is integrally formed with thepixel electrode PX which is formed in the inside of the pixel region.

[0123] That is, the pixel electrode PX is constituted of a groupconsisting of a plurality (two pieces in the drawing) of electrodeswhich extend in the y direction and are arranged in parallel in the xdirection in the inside of the pixel region. Among a group of thesepixel electrodes PX, one end of one pixel electrode PX also functions asthe source electrode SD2, while the other end portion of the pixelelectrode PX is electrically connected to the corresponding otherportion of the other pixel electrode PX.

[0124] Although not shown in the drawing, at interfaces between thesemiconductor layer AS and the drain electrode SD1 as well as the sourceelectrode SD2, thin layers which are doped with impurities of highconcentration are formed and these layers function as contact layers.

[0125] These contact layers may be formed such that, for example,impurity layers of high concentration are already formed on the surfaceof the semiconductor layer SD at the time of forming the semiconductorlayer SD, and using patterns of the drain electrode SD1 and the sourceelectrode SD2 formed on an upper surface of the semiconductor layer SDas masks, the impurity layers which are exposed from the patterns areetched.

[0126] On the surface of the transparent substrate SUB1 on which thethin film transistors TFT, the drain signal lines DL, the drainelectrodes SD1, the source electrodes SD2 and the pixel electrodes PXare formed, a protective film PSV (see FIG. 1 and FIG. 4) is formed.This protective film PSV is a film which is provided for obviating thedirect contact between the thin film transistors TFT and the liquidcrystal so as to prevent the deterioration of characteristics of thethin film transistors TFT.

[0127] Here, the protective film PSV is constituted of a sequentiallylaminated body consisting of a protective film PSV1 which is made of aninorganic material layer such as SiN and a protective film PSV2 which isformed of an organic material layer made of resin or the like. Thereason that the protective film PSV2 which is made of the organicmaterial layer is used as the protective film PSV in this manner is thatthe protective film PSV2 can reduce the dielectric constant of theprotective film PSV per se.

[0128] Accordingly, it is needless to say that the protective film PSVmay be wholly constituted of the organic material layer without usingthe inorganic material layer in part.

[0129] The counter electrodes CT are formed on an upper surface of theprotective film PSV. Each counter electrode CT is constituted of a groupconsisting of a plurality of electrodes (three electrodes in thedrawing) which extend in the y direction and are arranged in parallel inthe x direction in the same manner as the above-mentioned pixelelectrode PX. Further, these respective electrodes are positionedbetween the pixel electrodes PX when viewed as a plan.

[0130] That is, the counter electrodes CT and the pixel electrodes PXare respectively arranged equidistantly in the order of the counterelectrode CT, the pixel electrode PX, the counter electrode CT, thepixel electrode PX, . . . , counter electrode CT from the drain signalline DL at one side to the drain signal line DL at the other side.

[0131] Here, the counter electrodes CT which are positioned at bothsides of the pixel region have portions thereof formed such that theportions are overlapped to the drain signal lines DL and, at the sametime, the counter electrodes CT are formed in common with thecorresponding counter electrodes CT in the neighboring pixel regions.

[0132] In other words, the counter electrodes CT are overlapped to thedrain signal lines DL such that the central axes of the drain signallines DL are substantially aligned with the center axes of the counterelectrodes CT and a width of the counter electrodes CT is set largerthan a width of the drain signal lines DL. The counter electrode CTdisposed at the left side with respect to the drain signal line DLconstitutes one of respective counter electrodes CT of the left-sidepixel region, while the counter electrode CT at the right sideconstitutes one of respective counter electrodes CT of the right-sidepixel region.

[0133] By forming the counter electrodes CT having a width wider thanthat of the drain signal lines DL over the drain signal lines DL in thismanner, it is possible to obtain an advantageous effect that lines ofelectric forces from the drain signal lines DL terminate at the counterelectrodes CT and the termination of lines of electric forces to thepixel electrodes PX can be prevented. This is because that when thelines of electric forces from the drain signal lines DL terminate at thepixel electrodes PX, this gives rise to noises.

[0134] Respective counter electrodes CT each of which is constituted ofa group of electrodes are integrally formed with counter voltage signallines CL made of the same material as the counter electrode CT. Thecounter voltage signal lines CL are formed such that the counter voltagesignal lines CL sufficiently cover the gate signal lines GL. Thereference voltage is supplied to the counter electrodes CT through thesecounter voltage signal lines CL.

[0135] Here, the counter electrodes CT and the counter voltage signallines CL may be formed of a non-light-transmitting material such as ametal layer or a light transmitting material such as ITO (Indium TinOxide), ITZO (Indium Tin Zinc Oxide), IZO (Indium Zinc Oxide) or thelike, for example.

[0136] The counter voltage signal line CL is formed such that thecounter voltage signal line CL sufficiently covers the gate signal lineGL. The counter voltage signal line CL has a portion which is projectedfrom the gate signal line GL. Below such a projected portion of thecounter voltage signal line CL, a connecting portion with each pixelelectrode PX is positioned. Due to such a constitution, a capacitiveelement Cstg which uses the insulation film GI and the protective filmPSV as dielectric films is formed between the pixel electrode PX and thecounter voltage signal line CL.

[0137] The capacitive element Cstg is provided with a function ofstoring video signals supplied to the pixel electrode PX for arelatively long period or the like, for example.

[0138] Then, on the upper surface of the transparent substrate SUB1 onwhich the counter electrodes CT are formed, an orientation film ORI1 isformed such that the orientation film ORI1 also covers the counterelectrodes CT. The orientation film ORI1 is a film which comes intodirect contact with the liquid crystal and determines the initialorientation direction of molecules of the liquid crystal with a rubbingformed on a surface thereof.

[0139] As shown in FIG. 3, respective pixel electrodes PX and counterelectrodes CT are constituted such that they have a plurality of bentportions in the longitudinal direction so as to form a zigzag pattern.That is, the liquid crystal display device adopts a so-calledmulti-domain method.

[0140] That is, even when the liquid crystal has the same moleculararrangement state, the polarization state of the transmitting light ischanged in response to the incident direction of light incident to theliquid crystal display panel and hence, the transmissivity of light ischanged in response to the incident direction.

[0141] When a viewing point is inclined obliquely with respect to theviewing angle direction, such a viewing angle dependency of the liquidcrystal display panel induces a luminance inverting phenomenon so thatthe liquid crystal display device exhibits the display characteristicsthat images are colored in color display.

[0142] Accordingly, using an imaginary line which connects the bentpoints of respective electrodes as a boundary and the direction of theelectric field which acts between respective electrodes is madedifferent from each other between one region and the other region sothat it is possible to compensate for the coloring of images dependingon the viewing angle.

[0143] In the liquid crystal display device having such a constitution,each drain signal line DL has a trapezoidal cross-section in whichtapers which are gradually widened toward a ground layer side are formedon respective side wall surfaces which are arranged parallel to thelongitudinal direction.

[0144] Further, the drain signal lines DL are sufficiently covered withthe counter electrodes CT which are formed over the drain signal linesDL by way of the protective film PSV.

[0145] Based on the above-mentioned constitution, as shown in FIG. 5,assuming a distance from a top portion of the drain signal line DL tothe counter electrode CT as d1, a distance from the side wall faces ofthe drain signal line DL to the counter electrode CT becomes d2 and thisvalue is larger than d1.

[0146] This implies that under the restriction that a film thickness ofthe protective film PSV must be set to a given thickness, under therestriction that a cross-sectional area of the drain signal line DL mustbe set to a given value in view of the necessity for setting an electricresistance value of the whole drain signal line DL, and under therestriction that the width of the drain signal line DL must be set to agiven value to enhance the numerical aperture of the pixel region, thecapacitance between the drain signal line DL and the counter electrodeCT can be reduced.

[0147] That is, to reduce the capacitance between the drain signal lineDL and the counter electrode CT, first of all, an idea to increase thethickness of the protective film PSV is considered. However,corresponding to the increase of the thickness of the protective filmPSV, the strength of electric field between the pixel electrode PX andthe counter electrode CT is decreased and hence, the driving voltagemust be increased. Accordingly, the increase of the thickness of theprotective film PSV is restricted. Further, there may be considered anidea in which the width of the drain signal line DL is increasedcorresponding to the decrease of the film thickness of the drain signalline DL so as to reduce the capacitance between the drain signal line DLand the counter electrode CT while ensuring the electric resistancevalue of the drain signal line DL. In this case, however, along with theincrease of the width of the drain signal line DL, it becomes necessaryto increase the width of the counter electrode CT (since the counterelectrode CT has a so-called shielding function) and hence, thenumerical aperture of the pixel region is reduced.

[0148] In view of the above, when the cross-sectional area of the drainsignal line DL is set with respect to the constitution of the drainsignal line DL, it is effective to reduce the width W₁ of the topsurface with respect to the width W₂ of the bottom surface. This isbecause that a region where the distance from the side wall surface ofthe drain signal line DL to the counter electrode CT is d2 (>d₁) becomeslarger than a region where the distance from the top surface of thedrain signal line DL to the counter electrode CT is dl with respect toarea.

[0149] Also in this case, it is needless to say that the width W₂ of thebottom surface of the drain signal line DL is restricted by a givennumerical aperture which is to be obtained by the pixel region.

[0150] Embodiment 2

[0151] In view of the gist of the invention described in the embodiment1, the cross-sectional shape of the drain signal line DL is not alwayslimited to the trapezoidal shape. For example, as shown in FIG. 6(a), arecessed portion DEN which is extended along the longitudinal directionof the drain signal line DL may be formed on the top surface of thedrain signal line DL. Further, as shown in FIG. 6(b), the number of therecessed portion DEN is not limited to 1 but can be set to a pluralnumber. Still further, a cross-sectional shape of the recessed portionDEN is not limited and may be a triangular shape as shown in FIG. 6(c).

[0152] That is, provided that the surface of the drain signal line DLwhich faces the counter electrode CT has at least two regions where thedistance from the counter electrode CT differs from each other, the sameadvantageous effect can be obtained.

[0153] Embodiment 3

[0154]FIG. 7 is a constitutional view showing another embodiment of theliquid crystal display device according to the present invention andcorresponds to FIG. 5.

[0155] The constitution which makes this embodiment differ from theembodiment shown in FIG. 5 lies in that the drain signal line DL has atwo-layered structure, wherein tapers are formed on side wall faces of ametal layer DML which constitutes a lower layer by making use of a metallayer UML which constitutes an upper layer.

[0156] Here, as a material of the metal layer which constitutes theupper layer, Mo, Cr, MoW, MoCr, Ti, CoMo or the like can be selected,for example. On the other hand, as a material of the metal layer whichconstitutes the lower layer, Al, AlNd, AlSi, AlTa, AlTiTa, Cr or thelike can be selected, for example.

[0157]FIG. 8 is a flow chart showing one embodiment of a manufacturingmethod of the above-mentioned drain signal line.

[0158] First of all, as shown in FIG. 8(a), to form the drain signalline DL, a metal layer DML which constitutes a lower layer and a metallayer UML which constitutes an upper layer are formed sequentially on anupper surface of a ground layer. In this case, the metal layer UML whichconstitutes the upper layer is made of a material which exhibits afaster etching rate than a material of the metal layer DML whichconstitutes the lower layer.

[0159] Then, a photo resist film PRE is formed on a whole region of asurface of the metal layer UML which constitutes the upper layer and thephoto resist film PRE is made to remain on a region where the drainsignal line DL is to be formed using a well-known photolithographytechnique.

[0160] Subsequently, as shown in FIG. 8(b), using the remaining photoresist film PRE as a mask, the metal layers UML, DML which constitutethe upper layer and the lower layer are collectively etched.

[0161] First of all, the metal layer UML which constitutes the upperlayer is selectively etched so as to expose a surface of the metal layerDML which constitutes the lower layer.

[0162] Then, as shown in FIG. 8(c), the metal layer DML whichconstitutes the lower layer is etched. The etching is performed, asshown in FIG. 8(d), until a surface of the ground layer is exposed.

[0163] In this case, on side wall faces of the metal layer DML whichconstitutes the lower layer which remains below the photo resist filmPRE, tapers which are flared toward the ground layer side are formed.

[0164] Thereafter, as shown in FIG. 8(e), by removing the photo resistfilm PRE completely, the formation of the drain signal line DL iscompleted.

[0165] Embodiment 4

[0166]FIG. 9 is a constitutional view showing another embodiment of theliquid crystal display device according to the present invention andcorresponds to FIG. 5.

[0167] The constitution which makes this embodiment differ from theembodiment shown in FIG. 5 lies in that a drain signal line isconstituted of a metal layer having a three-layered structure, wherein awidth of a metal layer DML which constitutes a lowermost layer is set toW₂, a width of a metal layer UML which constitutes an uppermost layer isset to W₁ (W₂>W₁) and a width of a metal layer MML which constitutes anintermediate layer is changed from W2 to W1 in the direction from theside of the metal layer DML which constitutes the lowermost layer to theside of the metal layer UML which constitutes the uppermost layer thusforming tapers.

[0168] The metal layer MML which constitutes the intermediate layer isconstituted of Al or an Al alloy, while other metal layers UML, DML areconstituted of metal or an alloy thereof other than Al or the Al alloy.

[0169] In this case, it is preferable that other metal layers UML, DMLare constituted of metal or an alloy thereof which can suppress theoxidation of Al or the alloy thereof. This is because that Al or thealloy thereof is liable to be easily oxidized and the connectionresistance at an input terminal portion of the drain signal line isincreased and this may cause the distortion of waveforms of the videosignals.

[0170] Embodiment 5

[0171]FIG. 10 is a constitutional view showing another embodiment of theliquid crystal display device according to the present invention andcorresponds to a cross-sectional view taken along a line X-X in FIG. 3.

[0172] In this embodiment, the drain signal line DL adopts athree-layered structure in the same manner as the embodiment 4 and, atthe same time, an interlayer INV which is served for connecting thecounter voltage signal line CL and the counter electrode CT is formedsimultaneously with the formation of the drain signal line DL.

[0173] Here, the interlayer INV is constituted of a laminated structureconstituted of metal layers equal to those of the drain signal line DL.In this case, respective metal layers UML, DML which constitute anuppermost layer and a lowermost layer may be respectively selectedaiming at the enhancement of contacts between them and the counterelectrode CT and the counter voltage signal line CL.

[0174] For example, respective metal layers DML, UML constituting theuppermost layer and the lowermost layer are formed of MoZr, wherein itis desirable that an amount of Zr is smaller than an amount of Mo. To bemore specific, it is preferable that the composition is set to Mo-8 wt%Zr. Further, an intermediate layer is formed of AlNd, wherein it isdesirable that an amount of Nd is smaller than an amount of Al. To bemore specific, it is preferable that the composition is set to Al-9.8 wt%Nd.

[0175] Further, it is also possible to obtain the same advantageouseffect by using a so-called rare-earth element in place of Zr or Nd.

[0176] Further, it is preferable that the film thicknesses of respectivemetal layers UML, DML which constitute the uppermost layer and thelowermost layer are smaller than the thickness of the metal layer MMLwhich constitutes the intermediate layer. This is because that such astructure can enhance the reduction of resistance and the capacitancereduction effect due to the shape. In view of the above, it ispreferable that the film thickness of the metal layer MML constitutingthe intermediate layer is set to a value which is equal to or more thanfour times the film thickness of the metal layer UML which constitutesthe uppermost layer.

[0177] Embodiment 6

[0178] This embodiment shows a modification of the drain signal line DLhaving the three-layered structure shown in FIG. 5. This embodiment is,as shown in FIG. 11, characterized in that oxide films OXL are formed ontapered surfaces. This provision is made for preventing a phenomenonthat when the metal layer MML which constitutes the intermediate layermade of Al or an alloy thereof is exposed, a hillock occurs from themetal layer MML.

[0179] Accordingly, it is possible to prevent the occurrence of aphenomenon that the line resistance which constitutes the intermediatelayer is oxidized as time lapses and the line resistance of the drainsignal lines DL is changed whereby the reliability of the liquid crystaldisplay device is enhanced.

[0180] Here, the oxide films OXL can be formed by following methods.First of all, by bringing the drain signal line DL having athree-layered structure which forms tapers on the side wall facesthereof into an oxygen plasma treatment, the oxide films OXL can beformed on the tapered side wall faces. In this case, it is preferable touse non-Al based metal as a material of the metal layer UML whichconstitutes the uppermost layer. This is because that the non-Al basedmetal can prevent the increase of connection resistance.

[0181] As another method, a so-called anodizing processing is performed.That is, after forming the drain signal lines DL each having thethree-layered structure which uses an Al-based metal layer as theintermediate layer and forms tapers at side wall faces thereof on thesubstrate, the substrate is immersed into an electrolytic solution.Here, the drain signal line DL constitutes an anode and a metal platewhich constitutes a cathode is simultaneously immersed into theelectrolytic solution. Then, by supplying electricity to the anode andthe cathode, the anodic oxide films OXL are formed on the tapered sidewall faces. Also in this case, it is preferable that the material of themetal layer UML which constitutes the uppermost layer is formed ofnon-Al based metal.

[0182] Further, as still another method, by heating the drain signalline DL having the three-layered structure which forms tapers on sidewall faces thereof under atmosphere where oxygen is present, thermallyoxidized films are formed on the side wall faces. In this case, it isdesirable that heating is performed at a temperature of not more than100 degree centigrade.

[0183] Due to such heating, it is possible to alleviate stress generatedin the inside of the drain signal line DL having a multi-layeredstructure. This implies that the disconnection due to stress whichoccurs with respect to the drain signal line DL after use of the drainsignal line DL for a long period can be decreased.

[0184] This method can be used simultaneously with the above-mentionedtwo other methods. This is because that by adding the heating step, thestress generated in the inside of the drain signal line DL can bealleviated.

[0185] Embodiment 7

[0186] This embodiment adopts a structure in which, while the drainsignal lines DL maintain the rectangular cross section as it is as inthe case of conventional liquid crystal display device as shown in FIG.12, recessed portions are formed in regions on a surface of theprotective film PSV which constitutes the ground layer for the counterelectrodes CT above the drain signal lines DL except for regions wherethe counter electrodes CT (at least the counter electrodes CT which areoverlapped to the drain signal lines) are formed.

[0187] Such protective film PSV can be formed without increasing thenumber of steps using a photolithography technique which adopts aso-called half exposure method.

[0188] Also due to such a constitution, the distance between the drainsignal line DL and the counter electrode CT can be increased and hence,the capacitance between the drain signal line DL and the counterelectrode CT can be reduced.

[0189] Embodiment 8

[0190] This embodiment, as shown in FIG. 13, premises the constitutionshown in the embodiment 7, wherein tapers are formed on side wall facesof the drain signal line DL. Due to such a constitution, the capacitancegenerated between the drain signal line DL and the counter electrode CTcan be further reduced.

[0191] Also in this case, the drain signal line DL may be constituted ina multi-layered structure to obtain the advantageous effects describedin the above-mentioned embodiments.

[0192] Embodiment 9

[0193] Although the present invention has been explained by focusing onthe drain signal lines DL in the above-mentioned respective embodiments,it is needless to say that the present invention is not limited to thedrain signal lines DL and is applicable to the gate signal lines GL.

[0194] This is because that when the counter voltage signal lines CLwhich are connected to the counter electrodes CT are present over thegate signal lines GL, the capacitance between them becomes undesirableand there arises the same situation as in the case of the drain signallines DL.

[0195] Embodiment 10

[0196] In the above-mentioned embodiments, with respect to the drainsignal lines DL and the gate signal lines GL, the tapers formed on sidewall faces are formed on side wall faces of respective sides extendingin the running direction of the signal lines. However, it is needless tosay that the present inventions are not limited to such taper formationand are applicable to the taper formation in which the taper is formedon one of side wall faces.

[0197] As can be clearly understood from the foregoing explanations,according to the liquid crystal display devices of the presentinventions, the capacitance of the drain signal lines with respect tothe counter electrodes can be reduced, for example.

What is claimed is:
 1. A liquid crystal display device comprising: apair of substrates with liquid crystal layer therebetween; a pluralityof gate signal lines and a plurality of drain signal lines formed on oneof the pair of substrates; at least a pixel electrode and a plurality ofcounter electrodes formed on the one of the pair of substrates in eachpixels; wherein at least one of the plurality of counter electrodesextend along a drain signal line overlapping to the drain signal lineswith at least one of an insulation film therebetween, and the drainsignal line has two or more regions which differ in distance between asurface of the drain signal line and the counter electrode.
 2. A liquidcrystal display device comprising: a pair of substrates with liquidcrystal layer therebetween; a plurality of gate signal lines and aplurality of drain signal lines formed on one of the pair of substrates;at least a pixel electrode and a plurality of counter electrodes formedon the one of the pair of substrates in each pixels; wherein at leastone of the plurality of counter electrodes extend along a drain signalline overlapping to the drain signal lines with at least one of aninsulation film therebetween, the drain signal line has at least a taperportion in a cross section view at width direction of the drain signalline.
 3. A liquid crystal display device according to claim 2, wherein awidth of the drain signal line is wider at a substrate side of the drainsignal line formed thereon than a liquid crystal layer side.
 4. A liquidcrystal display device according to claim 2, wherein the drain signalline have a multiplayer structure of a lower layer faced to thesubstrate and an upper layer, and the width of the lower layer is widerthan a width of the upper layer.
 5. A liquid crystal display devicecomprising: a pair of substrates with liquid crystal layer therebetween;a plurality of gate signal lines and a plurality of drain signal linesformed on one of the pair of substrates; at least a pixel electrode anda plurality of counter electrodes formed on the one of the pair ofsubstrates in each pixels; wherein the drain signal line has athree-layered structure in which an intermediate layer is formed of aconductive layer made of Al or an alloy thereof and an uppermost layerand a lowermost layer are formed of conductive layers made of materialother than Al or an alloy thereof, at least one of the plurality ofcounter electrodes extend along a drain signal line overlapping to thedrain signal lines with at least one of an insulation film therebetween,and width of the lowermost layer is wider than a width of the uppermostlayer, and a width of the intermediate layer gradually change its fromthe width of the lowermost layer to the width of the uppermost layer. 6.A liquid crystal display device according to claim 5, further comprisingoxide films formed on the side wall of the surface of the intermediatelayer.
 7. A liquid crystal display device comprising: a pair ofsubstrates with liquid crystal layer therebetween; a plurality of gatesignal lines and a plurality of drain signal lines formed on one of thepair of substrates; at least a pixel electrode and a plurality ofcounter electrodes formed on the one of the pair of substrates in eachpixels; wherein at least one of the plurality of counter electrodesextend along a gate signal line overlapping to the gate signal lineswith at least one of an insulation film therebetween, the gate signalline has at least a taper portion in a cross section view at widthdirection of the gate signal line.
 8. A liquid crystal display deviceaccording to claim 7, wherein a width of the gate signal line is widerat a substrate side of the gate signal line formed thereon than a liquidcrystal layer side.
 9. A liquid crystal display device according toclaim 8, wherein the gate signal line have a multiplayer structure of alower layer faced to the substrate and an upper layer, and the width ofthe lower layer is wider than a width of the upper layer.
 10. A liquidcrystal display device comprising: a pair of substrates with liquidcrystal layer therebetween; a plurality of gate signal lines and aplurality of drain signal lines formed on one of the pair of substrates;at least a pixel electrode and a plurality of counter electrodes formedon the one of the pair of substrates in each pixels; wherein the gatesignal line has a three-layered structure in which an intermediate layeris formed of a conductive layer made of Al or an alloy thereof and anuppermost layer and a lowermost layer are formed of conductive layersmade of material other than Al or an alloy thereof, at least one of theplurality of counter electrodes extend along a gate signal lineoverlapping to the gate signal lines with at least one of an insulationfilm therebetween, and width of the lowermost layer is wider than awidth of the uppermost layer, and a width of the intermediate layergradually change its from the width of the lowermost layer to the widthof the uppermost layer.
 11. A liquid crystal display device according toclaim 10, further comprising oxide films formed on the side wall of thesurface of the intermediate layer.